Telephone operator's device. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Telephone operator's device. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Telephony

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In the literature, you can find descriptions of various devices for checking and repairing telephone sets, both with their connection to PBX lines, and autonomously. However, many of them are quite complex. The author of the proposed development has set himself the goal of creating the simplest stand-alone device with broad capabilities.

Using this device, you can, without connecting to the PBX lines, check the operation of electromechanical bells and electronic ringing devices of telephone sets (SLT), their speaking units and dialers. The device can autonomously test not only fully equipped disk and push-button SLTs (including cordless ones), but also separately disk dialers, as well as PDT-1, PDT-2, PDT-Z.DP-1 diode circuit separation attachments used on paired lines .

The scheme of the device is shown in fig. 1. It consists of three main components: a telephone line simulator, a dial tone generator, and a dial pulse recorder. The operating mode is selected by switch SA2. In the upper (according to the diagram) position of its mobile contact, the "Answering station" mode is enabled, and in the lower position - "Checking the dialer". There is an auxiliary mode "Call test", activated by pressing the SB2 button in any of the main modes.

Operator's device

The line simulator consists of diodes VD1-VD4, capacitor C1, resistors R1-R3, relay windings K1 and K2. While the tube of the TA connected to the device is not removed, the constant voltage at its terminals is 60 V. When the tube is lifted, it drops to 5 ... 15 V, depending on the type of TA.

The signal generator "Station response" with a frequency of approximately 400 Hz is assembled on transistors VT1 and VT2. The frequency can be changed by selecting the value of the resistor R4. This signal is fed to the output of the device through an isolating transformer T2. Since the power supply to the generator is supplied through the SA2 operation mode switch and the K1.1 relay contacts, the operation of this relay when the handset is picked up causes a continuous beep in the phone.

For the purpose of simplification, an alternating voltage with a frequency of 50 Hz from the secondary winding of the transformer T1, connected to the SLT by the contacts of the SB2 button, was used as a ringing signal.

The dial pulse recorder is assembled on a decimal counter with a DD1 decoder and a seven-element LED indicator HG1. The dialing pulses from the movable contact of relay K2.1 are fed to the counting input DD1. By pressing the SB1 button, the counter is returned to its original zero state.

One of the variants of the device is mounted on a board from a TA-68 telephone set (Fig. 2), from which all elements are removed, with the exception of the lever switch, which acts as an SB2 button, and the conversation node transformer (it is used as T2). The SB1 button is absent in this version; to set the counter DD1 to its initial state, press the lever switch of the tested TA the required number of times.

Operator's device

The alternating voltage on the winding II of the transformer T1 is 50 ... 60 V, on the winding III - 8 ... 10 V. Transformer T2 - from the conversational node of the TA-68 device, winding I - with a smaller number of turns, II - with a large . Any diodes VD1-VD8 for a current of at least 50 mA with a permissible reverse voltage of at least 100 V. Relays K1 and K2 - RES55A, passport RS4.569.600-02, RS4.569.600-07 or

RS4.569.600-11. Transistors VT1 and VT2 - any low-power corresponding structure.

The adjustment of the device begins with the installation of a voltage of 60 V at its output by selecting the value of the resistor R3. If you close the clamps for connecting the TA to each other, the PA1 milliammeter should show a current of 30 ... 40 mA. This is achieved by selecting the values of the resistors R1 and R2.

Having connected the tested TA to the device, turn on the power supply of the latter with the SA1 switch. Without lifting the handset, you can check the operation of the ringing device (call) by pressing the SB2 button. Next, set the SA2 switch to the "Answer station" position. When lifting the TA tube, a continuous beep should be heard in it, and the PA1 microammeter should show the current flowing through the device. Then, SA2 is moved to the "Check Dialer" position. Before dialing each digit, using the SB1 button, zero is set on the HG1 indicator. At the end of dialing, the number on the indicator should correspond to the dialed one. When checking electronic SLTs, it is useful to swap their terminals, as some faults manifest themselves differently depending on the polarity of the connection.

Three- and five-wire disk dialers are checked by connecting their red and yellow wires to the terminals of the device in the "Dialer Test" mode. They are convinced of the serviceability of the prefixes of the diode separation of the circuits by connecting them with observance of polarity between the device (the top wire in the diagram is positive) and a known-good TA. In this case, the "Answer station" mode must be enabled. It is not possible to check the ringer of an SLT connected in this way.

The device was tested when checking telephone sets TA-70, Spektr-201 M, PANASONIC KX-TCM943, attachments for diode separation of circuits DP-1, rotary dialers of various types.

Author: R. Yareshko, Kharkov, Ukraine

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